Device for the delivery of predetermined weft lengths in a shuttleless weaving machine

ABSTRACT

A device for the delivery of predetermined weft lengths through the weft conveyor of a shuttleless weaving machine, provided with means for drawing the weft yarn from a yarn cop and supplying it to an air operated buffer reservoir of the type which is adapted to form a reserve loop out of the yarn supplied, a thread clamp being provided between the buffer reservoir and the weft conveyor in the path of the reserve loop leg extending from the buffer reservoir to the weft conveyor, wherein the buffer reservoir cooperates with at least one thread detector controlling the yarn drawing means.

United States Patent 1191 Kaalverink 1 DEVICE FOR THE DELIVERY OF PREDETERMINED WEFT LENGTHS IN A SHUTTLELESS WEAVING MACHINE [75] Inventor: Gerardus Hendrikus Kaalverink,

Asten, Netherlands [73] Assignee: Ruti-Te Strake B.V., Deurne, Netherlands [22] Filed: Dec. 20, 1973 [21] Appl. No.: 426,557

[30] Foreign Application Priority Data Dec. 22. 1972 Netherlands 7217617 [52] U.S. C1 139/122 H; 226/97 [51] Int. Cl. .Q. D03D 47/36 [58] Field of Search 139/122 R, 122 H, 127 P;

[56] References Cited UNITED STATES PATENTS 3,580,444 5/1971 Mullekom 226/97 PICKING CONTROL 1451 Sept. 30, 1975 3,669,328 6/1972 Castelli 139/122 11 FOREIGN PATENTS OR APPLICATIONS 1.510.153 12/1967 France 139/122 1-1 Primary Examiner-Henry S. Jaudon Attorney, Agent, or Firm-Marshall & Yeasting [5 7 ABSTRACT A device for the delivery of predetermined weft lengths through the weft conveyor of a shuttleless weaving machine, provided with means for drawing the weft yarn from a yarn cop and supplying it to an air operated buffer reservoir of the type which is adapted to form a reserve loop out of the yarn supplied, a thread clamp being provided between the buffer reservoir and the weft conveyor in the path of the reserve loop leg extending from the buffer reservoir to the weft conveyor, wherein the buffer reservoir cooperates with at least one thread detector controlling the yarn drawing means.

4 Claims, 4 Drawing Figures US. Patent Sept. 30,-1 75- shag-18g U.S. Pat ent Sept. 30,1975 Sheet2 0f2 3,908,707

FIG. 3

DEVICE FOR THE DELIVERY'OF V ,PREDETERMINED WEFT LENGTHSIN A SHUTTLELE-SS WEAVING MACHINE BACKGROUND or TI-IE INYENTION I .The invention relates to-a 'device'fonthe delivery of the thread clamp respond very accurately and to a large redetermined weft lengths, through the'weft conveyor" )uffer reservoir and the weftconveyor in. the-path of I he reserve-loop leg extending from-the buffer reservoir 0 the weft conveyor.

Yarn preparation devices of this type 'are ltnown. The

Iarn drawing device is generally formed therein by a )air of cooperating measuring rollers: for continuously lrawing the yarn from the yarn cop and supplying it to he buffer reservoir. The yarnloop, whichis formed in he buffer reservoir, is then intermittently processed,

namely during the weft inserting phase .of a weaving cy- :le, by the weft conveyor, and-a thread clamp is .pro-

'ided which is opened at the start of the weft inserting ihase and again closed at the end thereof.

SUMMA Y OF THE INVENTION,

The device according to the invention is characterzed in that the buffer reservoir cooperates with at least" me thread detector controlling the yarn drawing neans.

This implies that in the device according to the invenion the yarn drawing means are notcontinuouslyoperlting, but are only energized after the loop length, pres- :nt in the buffer reservoir, has decreased to less than he maximum loop length corresponding with the posiion of the thread detector, and remain operative until he loop length in. the buffer reservoir has again in-' :reased to the length determined by the position of the hreaddetector. Adecrease in the loop length present n the buffer reservoir is effected each time when the hread clamp opens and the weft conveyor is permitted 0 draw yarn from the buffer reservoir. Since the drawng, of the yarn occurs according to the momentary teed, the weft conveyance and therefore the opening vnd closing of the thread clamp may take place accordng to any desired program. The device according ,to he invention is therefore also particularly suitable for .pplication to weaving with different colors. Then for extent reproducably to-the sig'nal'emitted by theweft detector. For this-purpose it is'adv'antageousto' use a yarn clamp of the type described in Dutch patent apple cation 7217620, corresponding'to' US. patent application Ser.-N0. 426,79-8,' fi'led Dec. 20, 1973';

Yarn drawing means of different types'ma'y be used in the device according to the inv entionflt is advanta geous to use a yarn drawing device'of 'the' type' de scribed'in US. Pat No. 3,853, l53namely by'directing that yarn drawing 'devicewith its output side towards" the entrance of the'buffer reservoir. Thereby'thesteepi starting characteristic of the-.electromotor 'of the quick response type, used in this yarn drawing device, is made use of, whereby the .yam='leng'th taken froin the buffer reservoir in 'a weft inserting phase is very quickly sup plemented to the desired length corresponding tothe" position" of the'thread detector in the buffer reservoir; so that highweft speeds are permitted.

A simple and at the same time easily controllable de vice is obtained if a blowing nozzle 'is used' asthe am drawing means, the air supply of this nozzle being con trolled by the thread detector. 1 t

Preferably the yarn draw-blowing nozzlecoo'perates with a yarn brake such that this yarn brake is'inoperative when the blowing nozzle is energized'and'becomes operative when theienergization of the blowing nozzle is interrupted.

In a practical embodiment the yarn brake is likewise constituted by a blowing nozzle, the blowingdirec'tion" to that'of theyarn draw-blowing thereof being opposite nozzle.

RIEF D E ECRIP TION oF 'TfHEbR AwINo sf,

FIG. 1 is a schematic the invention.

FIG. 2 is the wiring diagram thereof:

form of de'' FIG..3 is a perspective view of a preferred vice according to the invention;- 1

FIG. 4 is a sectional view of a preferred form of yarn" I clamp for use ina device according to'the invention.

In the drawing reference number 1 indicates a buffer reservoir, e.g. inthe formof asuction tube, whereas reference number 2 indicates a weft inserting jet or yarn conveyor in the form of a blowing nozzle and reference number 3 a thread clamp positioned between this blowing nozzle and the buffer reservoir 1; The 5 thread clamp .3 may vbeof any conventional construe;

tion, and the specifiostructure of the'thread' clamp 3*is' 2 view of the device according to i ach color to be woven a device of the just discussed ype-is applied. The thread clamps of these devices may hen be controlled corresponding to the desired color attern, the opening being e.g., carried out by a control ssembly programmed corresponding to the desired left pattern, and thereclosing occurringunder the ontrol of a weftdetector positioned in the weaving bed.

Contrary to the situation prevailing iria device with on tinuous drawing of the yarn, oftheknowntypede- :rib ed above, the length of the weft, whichis inserted no the weaving shed, is herein determined by the No. 7217620,.corresponding to US. patent application Ser. No. 426,798.

That yarn clamp is shown in cross section inFI'G. 4, I

and comprises a stationary and a movable clamping jaw 21 and 22; respectively. The stationary clamping jaw 21 is secured through a. rubber block 23 to'a projecting tread clamp between the buffer reservoir and the weft onveyor. In order topermit adjusting the yarn supply the weft conveyor as economicallyas possible and iereby to keep the loss of weft yarn, due to the cutting,

ff of the :ends thereof projecting beyond ,bothcloth dges, as'small as possible it is of course important that part 25 of a housing 24 to. be mounted-stationary, eLgi, on the-frame ofa weaving machine. t Y

The movable clamping jaw 22 is secured to the one end of a lever 26, preferably made from a light material, such. as aluminum, whichiis pivotally connected at its other end to the housing 24. The pivot connection ,is constituted by a leaf spring 27which is somewhat biased, namely so that the spring tends to rotate the lever clockwise as seen in the drawing.

An electric coil, indicated with the reference number 28, is preferably coiled to the shape of a flat spiral and is received in a bridge piece 29, preferably made of plastic, extending over the housing 24 and secured thereto. .The lever 26 extends below the bridge piece 29 and comprises at the position of the coil 28 a disc 30, e.g., of aluminum, which is suitable for induction therein of eddy currents when a current pulse is sent through the coil 28, In the open position of the yarn clamp, shown in the drawing, the lever 26 with the disc 30 is kept by the biased spring 27 against the coil 28.

At its lower side the lever 26 supports a second disc or block 31 of ferromagnetic material, which cooperates with the armature 33 of an electromagnet 32 mounted in the housing 24.

The described thread clamp operates as follows:

A current pulse supplied to the coil 28 results in that a large downwardly directed acceleration force is imparted to the disc 30, which force moves the lever 26 very quickly to the closing position. If now simultaneously with energizing the coil 28 the electromagnet 32 is energized, the lever 26 is thereafter kept in its closed position during the energization time interval of the electromagnet in that the ferromagnetic disc 31 is attracted by the electromagnet armature 33.

At the entrance of the buffer reservoir 1 a yarn drawing device 4, in the form of a blowing nozzle, is indicated, which is adapted ,to draw the weft yarn from the yarn cop when supplied with blowing air, in order to supply this yarn to the buffer reservoir 1 in which the yarn nestles in the shape of a loop L under the influence of the air flow I generated in the reservoir. The blowing nozzle 4 is of conventional construction, and consists of a converging annular passageway 4a into which compressed air is introduced so as to inject a converging jet of air into an outlet 4b. The thread, which extends freely through the blowing nozzle 4, coincides with the axis of the nozzle, and is propelled along the axis of the nozzle by the action of-the jet of air. In the embodiment shown a yarn brake 6, likewise in the form of a blowing nozzle, constructed in the same manner as the blowing nozzle 4, is indicated between the yarn draw-blowing nozzle 4 and the yarn cop 5, the purpose and the operation of which will be explained hereunder in detail.

The buffer reservoir 1 cooperates with a thread detector 7 comprising a light source 8, e.g., a Ga-As diode, and a light sensitive element, e.g., a light sensitive resistance or photodiode 9. The thread detector 7 is so positioned longitudinally of the buffer reservoir 1, that a length of the loop L, corresponding with this position, provides the yarn length which it is desired to have ready in the buffer reservoir at the moment at which the weft conveyor 2 has to start carrying out a weft inserting phase.

In the situation shown in the drawing the thread clamp 3, e.g., a yarn clamp of the type according to the patent application mentioned above, is closed, whereas the end of the yarn loop L is just to the right of the thread detector 7. This means that the light beam, emitted by the light source 8, is intercepted by the legs of the yarn loop L, so that the light sensitive element 9 receives a reduced amount of light. This situation corresponds to the position, as indicated in the drawing, of the air valve 10, e.g., in the form of a solenoid valve,

provided in the common air supply conduit 11 for the blowing nozzles 4 and 6. The air valve 10 is a conventional two-way solenoid-operated air distributing valve. In the situation shown in FIG. 1, the light sensitive element 9 is receiving a reduced amount of light, and the amplifier 12 is designed in the conventional manner so that under such conditions it does not supply a sufficient amount of current to energize the solenoid of the valve 10. In the position shown of the air valve 10 the air supply to the yarn draw nozzle 4 has been interrupted whereas the supply to the blowing nozzle 6 is open. The yarn loop L is at rest in this situation, in that the blowing nozzle 6 supplies sufficient resistance to prevent the air flow I from drawing yarn from the yarn cop 5, although the blowing nozzle 6 does not have sufficient powerto draw the yarn backward out of the reservoir 1.Thus the legs of said loop are kept taut by the operation of the air flow I and of the blowing nozzle 6 acting as a yarn brake or yarn clamp. This yarn loop is ready to be taken up by the weft conveyor, as soon as a weft inserting phase is desired, from the buffer reservoir 1 and to be conveyed through the weaving shed. The signal for this weft inserting phase is e.g., given by an electrical picking control which has been programmed according to the desired weft pattern, which signal opens the thread clamp 3. The start of the operation of the weft conveyor 2 results in that the end of the yarn loop L arrives to the left of the thread detector 7, whereby the light sensitive element 9 receives the undiminished light beam emitted by the light source 8 and (see the diagram according to FIG. 2) issues a signal which is supplied to the solenoid 10 via an amplifier 12, whereby said solenoid receives a sufficient amount of current so that it moves the two-way valve from the position shown in full lines in FIG. 1 to the position shown in broken lines, in which position the blowing air supply to the blowing nozzle 6 is interrupted and that to the yarn draw nozzle 4 is opened. From this moment on the blowing nozzle 4 draws yarn from the yarn cop 5 and supplies it to the buffer reservoir 1 until the end of the yarn loop L again arrives to the right of the thread detector 7, at which moment the drawing of the yarn is again interrupted. This will generally be the case a moment after the weft inserting phase has been completed and the thread clamp 3 has been closed again. This closing occurs e.g., under the control of a weft detector positioned at the end of the weaving shed remote from the blowing nozzle 2, which detector delivers a signal to the thread clamp 3 upon detecting the inserted weft.

FIG. 3 shows a weft detector, positioned at the end of the weaving shed, which like the thread detector 7 consists of a light source 8a and a light sensitive element 9a.

As stated hereinbefore it is advantageous to use a yarn drawing device of the type described in US. Pat. No. 3,853,153, by directing the yarn output of that device toward the entrance of the buffer reservoir 1. A yarn drawing device of that type is shown in FIG. 3, in which an electromotor 41 of the quick response type, e.g., a motor having a bell-shaped or disc-shaped armature, is mounted to one side of a motor support 42 seplied with air through a conduit schematically indi-' cated at 47. The weft blowing nozzle 2 has a tubular discharge section 20 facing the opening of the weaving shed 13 delimited by the upper andlower warp threads 50 and 51 respectively and by the retracted reed 52.

A pneumatic yarn control assembly 48, likewise carried by the motor support 42, is supplied with air through the schematically indicated conduit 49. Preferably this control assembly comprises a yarn-take-off injector and a braking injector known per se. When the solenoid valve is energized as hereinbefore described, the valve 10 will cause the supplied air to be bypassed to the left through the tubular injector 4, as a result of which suction is generated at the injector 4 to draw weft yarn from the cop 5. Upon deenergization of the solenoid valve 10, the supplied air will flow out through the braking injector 6 and thereby exert a braking force directed to the right on the weft yarn.

The weft yarn w extending from the left end of the yarn control assembly 48 in tangential relationship to the disc 45 is wound several times around the circumferential surface of this disc and then is directed toward the entrance of the buffer reservoir 1 as hereinbefore described. A guide element cooperating with the disc 45 keeps the yarn coils mutually separated.

The weft yarn leaving the buffer reservoir 1 in FIG. 3 extends through a thread clamp (which is hidden in FIG. 3) to the tubular inlet 2b of the weft inserting nozzle 2.

The operation of the apparatus shown in FIG. 3 is as described in connection with FIG. I, the motor 1 being controlled by the same signals as the solenoid valve 10, so that the motor 1 is energized at the same time as the solenoid valve 10.

As stated hereinbefore, each time the thread clamp opens. the weft conveyor is permitted to draw weft yarn from the buffer reservoir.

For the sake of simplicity, the weft inserting conveyor 2 has been considered to be supplied continuously with compressed air, as described in patent No. 3,853,153, so that the starting and stopping of the weft insertion is controlled entirely by the opening and clos ing of the yarn clamp 3. In order to conserve energy, however, the conventional practice of supplying air to the weft inserting nozzle 2 only during the weft inserting operation may be followed, using the signals which maintain the yarn clamp 3 open to simultaneously maintain the supply of compressed air to the weft inserting nozzle 2.

I claim:

l. A device for supplying weft yarn to a weft conveyor of a shuttleless weaving machine, comprising a. intermittently operable means for drawing weft yarn from a yarn cop,

b. an elongated buffer reservoir having at one end a mouth to which weft yarn is fed by said yarndrawing means and in which a length of the yarn is stored in the form of a loop having one leg extending from the buffer reservoir to the weft conveyor,

0. a yarn clamp arranged to engage said leg between the buffer reservoir and the weft conveyor,

(1. means for intermittently opening the yarn clamp to permit the weft conveyor to convey yarn drawn from the buffer reservoir,

e. a yarn detector arranged to detect the end of said loop in the buffer reservoir at a point remote from the mouth thereof, and l f. a control which is actuated by the yarn detector and which renders the yarn-drawing means inoperative when yarn is detected and operative when yarn is not detected, in order to cause the length of yarn in the buffer reservoir to be restored after yarn has been withdrawn from the buffer reservoir.

2. A device according to claim 1, wherein the yarndrawing means comprises a blowing nozzle the air supply of which is turned on by said control when yarn is not detected by the yarn detector.

3. A device according to claim 2, characterized in that the yarn draw-blowing nozzle is preceded by a yarn brake, and the control actuated by the yarn detector renders said brake operative when yarn is detected and inoperative when yarn is not detected.

4. A device according to claim 3, characterized in that the yarn brake is likewise constituted by a blowing nozzle, the blowing direction thereof being opposite to that of the yarn draw-blowing nozzle. 

1. A device for supplying weft yarn to a weft conveyor of a shuttleless weaving machine, comprising a. intermittently operable means for drawing weft yarn from a yarn cop, b. an elongated buffer reservoir having at one end a mouth to which weft yarn is fed by said yarn-drawing means and in which a length of the yarn is stored in the form of a loop having one leg extending from the buffer reservoir to the weft conveyor, c. a yarn clamp arranged to engage said leg between the buffer reservoir and the weft conveyor, d. means for intermittently opening the yarn clamp to permit the weft conveyor to convey yarn drawn from the buffer reservoir, e. a yarn detector arranged to detect the end of said loop in the buffer reservoir at a point remote from the mouth thereof, and f. a control which is actuated by the yarn detector and which renders the yarn-drawing means inoperative when yarn is detected and operative when yarn is not detected, in order to cause the length of yarn in the buffer reservoir to be restored after yarn has been withdrawn from the buffer reservoir.
 2. A device according to claim 1, wherein the yarn-drawing means comprises a blowing nozzle the air supply of which is turned on by said control when yarn is not detected by the yarn detector.
 3. A device according to claim 2, characterized in that the yarn draw-blowing nozzle is preceded by a yarn brake, and the control actuated by the yarn detector renders said brake operative when yarn is detected and inoperative when yarn is not detected.
 4. A device according to claim 3, characterized in that the yarn brake is likewise constituted by a blowing nozzle, the blowing direction thereof being opposite to that of the yarn draw-blowing nozzle. 